(a) Field of the Invention
The present invention relates to a method of producing a substrate coated with a film of liquid crystal material, which may be used for producing liquid crystal optical devices, including liquid crystal display devices, liquid crystal memory devices, and liquid crystal acoustic devices. The present invention further relates to a method of producing a liquid crystal optical device using the method of producing a substrate coated with a film of liquid crystal material, and to an apparatus to be used for the method of producing the liquid crystal optical device.
(b) Description of the Related Art
In common methods for coating a substrate with a film of liquid crystal material, offset lithography or a bar coater have been used for applying liquid crystal to substrates. For example, in Japanese Patent Application Kokai Koho (Laid-open) No. 64-6922, disclosed is a method using a kind of bar coater, wherein a liquid crystal is applied to a substrate using a bar or a spatula, thereby performing orientation treatment simultaneously using the shear force generated by the application. However, since the liquid crystal is directly applied as it is in the method, some liquid crystals having high viscosity, such as polymer liquid crystals, need reduction of application speed or heating during application, which decrease the productivity.
In Japanese Patent Application Kokai Koho (Laid-open) No. 60-75817, there is disclosed an efficient method of producing liquid crystal optical devices, by which a liquid crystal optical device is produced by applying a liquid crystal to a substrate using offset lithography and, thereafter, pressing an opposed substrate to the coated substrate. Offset lithography however has difficulties in producing thin film of liquid crystal and cannot always produce film of a good quality. Therefore, the method using offset lithography is unfit for production of devices requiring very thin cell thickness (less than several .mu.m), such as ferroelectric liquid crystal devices. The method has another problem that since the orientation techniques employed in the method, for example rubbing technique, require a step of slow cooling, the improvement of productivity is not particularly remarkable.